From f15dd0532e618469322f72b84e094a2ca70821de Mon Sep 17 00:00:00 2001
From: Mathieu Serandour <mathieu.serandour@telecom-paris.fr>
Date: Fri, 25 Mar 2022 20:44:28 +0100
Subject: [PATCH] schedule when irqs fire

---
 kernel/int/irq.c      |  8 ++++-
 kernel/int/irq.s      | 72 ++++++++++++++++++++++++++++++++++---------
 kernel/int/syscalls.c |  0
 kernel/int/syscalls.h |  0
 4 files changed, 64 insertions(+), 16 deletions(-)
 create mode 100644 kernel/int/syscalls.c
 create mode 100644 kernel/int/syscalls.h

diff --git a/kernel/int/irq.c b/kernel/int/irq.c
index 092e842..a4795aa 100644
--- a/kernel/int/irq.c
+++ b/kernel/int/irq.c
@@ -3,6 +3,7 @@
 #include "../lib/panic.h"
 #include "../lib/logging.h"
 #include "../lib/sprintf.h"
+#include "../sched/thread.h"
 
 #include "irq.h"
 
@@ -65,7 +66,7 @@ void release_irq(unsigned n) {
 }
 
 // called from irq.s
-void irq_common_handler(uint8_t irq_n) {
+void irq_common_handler(uint8_t irq_n, gp_regs_t* context) {
     assert(irq_n <= IRQ_END);
     assert(irq_n >= IRQ_BEGIN);
     // the irq_n th irq just fired
@@ -79,6 +80,11 @@ void irq_common_handler(uint8_t irq_n) {
     }
 
 
+    sched_save(context);
+
     handler(driver);
+
+    if(!schedule())
+        return;
 }
 
diff --git a/kernel/int/irq.s b/kernel/int/irq.s
index f22968c..8e954c3 100644
--- a/kernel/int/irq.s
+++ b/kernel/int/irq.s
@@ -1,20 +1,29 @@
 
 [extern irq_common_handler]
 
+
 ; macro argument: irq number
 %macro create_irq 1
 [extern _irq_handler%1]
 _irq_handler%1:
-    ; enter stack frame
-    ; push rbp
-    ; mov rbp, rsp
+; already pushed stuf:
+;    uint64_t RIP;
+;    uint64_t CS;
+;    uint64_t RFLAGS;
+;    uint64_t RSP;
+;    uint64_t SS;
 
 ; enter stack frame
     push rbp
-    mov rbp, rsp
-    push rdi
-    mov dil, byte %1
+    ; save stack pointer
     
+    ; save frame pointer and enter stack frame
+;    mov rbp, rsp
+    
+    ; save rax
+    push rax
+    mov al, byte %1
+
     jmp common_stub
     
 
@@ -41,33 +50,66 @@ create_irq 47
 
 common_stub:
 
-    push rax
+; clear DF flag
+;  DF need to be clear on function 
+; entry and exit (System-V ABI)
+    cld
+
+    ; save context
+    ; we already saved rsp, rbp, rax
+    ; here, al = the irq handler number
+
     push rcx
     push rdx
+    push rbx
     push rsi
+    push rdi
+
     push r8
     push r9
     push r10
     push r11
+    push r12
+    push r13
+    push r14
+    push r15
+
+
+
+    ; put the irq handler number in dil: the 
+    ; argument for the irq_common_handler function
+    mov dil, al
+
+    ; beginning of the interrupt stack = beginning of
+    ; the context structure 
+    mov rsi, rsp
+
 
-; clear DF flag
-;  DF need to be clear on function 
-; entry and exit (System-V ABI)
-    cld
 
     call irq_common_handler
 
+    ; restore the context
+    ; this function only returns
+    ; if no rescheduling is done
 
+
+
+    pop r15
+    pop r14
+    pop r13
+    pop r12
     pop r11
     pop r10
     pop r9
     pop r8
+
+    pop rdi
     pop rsi
+    pop rbx
     pop rdx
     pop rcx
     pop rax
-    pop rdi
-    ; mov rsp, rbp
-    ; pop rbp
-    leave
+    pop rbp
+
+
     iretq
\ No newline at end of file
diff --git a/kernel/int/syscalls.c b/kernel/int/syscalls.c
new file mode 100644
index 0000000..e69de29
diff --git a/kernel/int/syscalls.h b/kernel/int/syscalls.h
new file mode 100644
index 0000000..e69de29